If your muscles are all torn up, and then you stretch... well, wouldn't they tear more? Whenever I stretch while sore, it ends up lasting longer, and I also don't gain any flexibility out of it either. I won't even attempt dynamic stretching when sore because you're not supposed to dynamic stretch too lightly.

Check out Stretching Scientifically, Kurz goes into the benefits of stretching after a heavy workout in detail. I personally think that, while a brief stretch after a workout doesn't help with my soreness, it seems to improve my flexibility.

Stretching is a debated subject in itself. Some people just don't believe there's any benefit to it. (Which I believe is a ridiculous opinion)

Well when you are still sore after a a hard workout two days before, you can stretch but only limited. You will also notice that you will not be as flexible as the muscles that are sore are tense meaning you will not be able to stretch as much as you are normally acustom too. Therefore a light stretch can be applied but nothing more.Like Tom Kurz mentions in his book, you cannot do isometric training two days running as you muscles are still repairing themselves and need time to recover.Answer your question?

Unless you are a raw beginner who has never touched weights, you really shouldn't be getting the DOMS 2 days after training.

I don't agree. The physiological reactions to weight training occur over a roughly 48 hour period. Granted the intensity of doms should go down significantly after 36 hours, it is still not unreasonable to be sore 2 days after a work-out.

So then, as long as I'm working on my legs much.. I'll pretty much never achieve the side splits.

If static passive stretching requires consistency in order for me to make progress, then I won't be able to. Soreness won't allow me to stretch much. And when I'm not sore anymore, I've probably lost the small progress I've made.